Best Direction To Face Solar Panels — South or West?

The conventional wisdom (in the Northern Hemisphere) is that the best direction to face solar panels is south, since that is generally where they’d receive the most sunlight. However, the electricity system is not as simple as it sometimes seems, and the best direction to face solar panels may actually be west! Read on the get the details on this, including the results of some recent research.

Electricity supply and electricity demand have to match at all times in order for the grid to remain up and running. If they don’t match, get ready for a blackout. Also, it’s worth noting that there is actually an extremely small amount of energy storage on the grid. So, when demand rises and electricity supply from the cheapest power plants is stretched to its limits, more expensive electricity from power plants that can turn on when needed gets generated and put onto the grid.

The good news is that electricity usage on a large scale is rather predictable. (If it wasn’t, we’d see a lot more blackouts.) Demand is very low in the middle of the night and early in the morning. As people wake up and start doing things, electricity demand rises. In hot (and sunny) climates, electricity really ramps up as people turn on their air conditioning units. But all across the world, electricity demand follows an arc every day in which demand rises as the day gets going and falls as the day comes to a close. In many places quite a bit off the equator, it is highest from about the middle of the day until sometime in the early evening. Of course, there is some variation that depends on region, season, and other matters that can make demand peak a bit later or a bit earlier in that time frame.

Of course, solar power plants just generate electricity when there is sunlight. The good news, as you can see above, is that there’s sunlight at many of the times of greatest electricity demand, the times at which electricity would be most expensive. This makes electricity from “fuel-free” solar power plants extremely valuable. But that’s all just the back story — now, let’s get to the interesting point of the week, which is the best direction to face solar panels — the answer seems to go against a very long-held assumption regarding this matter.

The assumption is: more sunshine = more electricity = better, which would normally mean that it’s better to have solar panels facing south than east, west, or north. Well, as I think you’ve gathered by now, more electricity from sunshine at peak demand may trump more electricity overall. Indeed, recent research has found that it’s more useful in many places to have solar panels facing west in order to catch sunlight during electricity peak demand in the afternoon and early evening hours.

The research is the first of its kind to evaluate the energy production of solar panels oriented in different directions. Pecan Street analyzed 50 homes in the Austin, Texas area. Some had only south-facing panels, others had west-facing panels, and some had both.

Now, all of this is very important for utilities and legislators who are in charge of offering incentives for solar power or other measures that could reduce electricity demand at the height of the day.

However, in a growing number of places, this is already useful information for homeowners. Time-of-use (TOU) pricing is becoming more and more popular across the country. What TOU pricing does is it charges you much more when you use electricity at times of peak demand than when you use electricity at times of low demand.

So, in such places, if you can cut your grid electricity usage dramatically at times of peak demand (and peak pricing) by using rooftop solar power at that time instead, you can save some serious cash. It seems that west-facing solar panels would help you to do that to a much greater degree than generally recommend south-facing solar panels. “During times of peak demand, which is defined as 3 p.m. to 7 p.m. in Texas’s ERCOT territory, 84 percent of electricity in west-facing systems was used in the home.” Keep that in mind if you intend to go solar anytime soon!

And even if you don’t have TOU pricing in your region yet, note that there’s a decent chance you will get it in the future. It makes a lot of sense and is a growing trend. If you’re looking to maximize your revenue/savings from going solar, the best direction to face your solar panels may well be west. But be sure to consult with solar professionals in your region about this, to share this information with them, and to do as much as you can to understand the electricity pricing system and potential changes to that system in your region….